I've been considering for several years trying to push a kernel patch which would provide a way for userspace to find out when someone starts listening on some port. Based on problems I saw long ago in the late days of upstart and early days of systemd, that seemed like it would solve a not infrequent problem without having to make any changes to the daemons. Upstart tried to solve it by making the daemons send a sigstop when ready; systemd solves it by making the daemons support socket notification; listen-notifiers could be entirely handled by the dependency handler in the init system.
It's *still* on my list of todos. Maybe sufficient ridicule here will help me knock it off the list :) On Wed, Apr 01, 2020 at 08:23:26AM -0500, Brett Neumeier wrote: > I read on http://skarnet.org/software/s6/notifywhenup.html: > > "...daemons can simply write a line to a file descriptor of their choice, > then close that file descriptor, when they're ready to serve. This is a > generic mechanism that some daemons already implement." > > I am curious, does anyone on this list know of examples of such daemons? I > am considering creating and submitting patches for some daemon programs > that I use that do *not* support this mechanism as yet, and am curious if > it is as simple as it looks like it should be. > > Cheers! > > Brett > > -- > Brett Neumeier (bneume...@gmail.com)
